Hi there, same board/server (different opteron), 4 GB, only 3 GB too
(havent got access to BIOS atm to check what it sees, but pretty sure
it was more than 3 GB). Running first version of BIOS code, will be
updating it soon and will let u know if that makes any difference.

There was a discussion about this problem on this very list around
mid-august. Check the archives for "BIOS memory hole"

This is a larger hole than I would expect, though. That's why I was
interested in getting the SMAP table from this machine. Not sure why
his verbose output didn't include it.